北斗三号组网卫星数据质量分析及单系统定轨精度初步评估

选取2018-01-23起10 d内16个iGMAS测站观测数据,对北斗三号卫星的观测数据质量及BDS单系统精密定轨精度进行评估。初步结果表明,老信号B1I、B3I北斗三号卫星的信噪比略强于二号卫星,噪声与多路径基本相当,均在0.1 m量级,新卫星不存在星内多路径偏差。新信号B1C/L1/E1频点GPS信噪比最强,Galileo和BDS卫星相当,B2a/L5/E5a和B2b/E5b各系统基本相当;噪声及多路径方面,B1C/L1/E1频点GPS优于BDS、Galileo卫星0.1 m量级,B2a/L5/E5a和B2b/E5b各系统基本相当,均在0.1 m量级,新信号中北斗三号卫星星内多路径偏差基本消失。单系统精密定轨试验中,分别进行有/无GEO卫星策略、太阳光压模型ECOM 五/九参数策略的比较,并使用卫星激光测距数据进行独立检核。初步结果表明,有GEO卫星、ECOM五参数光压模型的定轨精度最好,C19号卫星7个重叠弧段的平均定轨精度在沿迹向、法向、径向的精度分别为32 cm、16 cm、8 cm,与试验卫星的定轨精度基本相当。     

长岛县南五岛土壤地球化学特征及环境质量评价

以长岛县南五岛土壤为研究对象,对区内土壤元素的含量特征进行分析,并对土壤环境质量进行评价。结果表明：研究区土壤平均含量与烟台市、山东省以及全国土壤平均水平相比,除CaO,Na2O,Hg,S,Se,P,F元素含量差异较明显,其他大部分元素含量相对稳定,元素含量的高低不仅与研究区背景条件有关,也与人类活动密切相关。研究区土壤环境质量整体较好,大部分区域属于清洁区和尚清洁区,仅城区局部受到一定程度的Cd,Hg,Zn污染。     

杭州城市生活质量的定量评价

以乡镇、街道为基本空间统计单元,选取人口密度、住宅基准地价、大专以上学历人口比重为社会经济指标,建设用地比重、NDVI、地表温度为生物物理指标,采用主成分分析和GIS叠加法,定量评价了杭州城市生活质量的空间分布状况。结果表明：NDVI和地表温度 (相关系数r = -0.63)、城镇用地比重 (相关系数r = -0.83) 呈明显的负相关,地表温度和城镇建设用地是影响杭州“绿色环境”两个的最重要因素。NDVI和住宅基准地价 (r = -0.66)、大学毕业生比例 (相关系数r = -0.59)、人口密度 (相关系数r = -0.29) 也呈较明显的负相关,“绿色环境”并未成为高学历人群和高收入家庭的主要决定因素,较繁华或较便利地段仍是高学历人群和高收入家庭选择居住环境的首要选择。高生活质量值 (前20%) 区域主要位于分布于城市中心区,即杭州上城区、下城区及西湖区的部分单元,而郊区的生活质量相对较低。     

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长沙都市区生境质量对城市扩张的时空响应

生境质量是评价生态环境的重要指标,掌握其对城市扩张的时空响应规律,有助于提升都市区城乡规划质量和生态管控的合理性。本文在运用InVEST模型对长沙都市区1995-2015年生境质量时空演化的基本特征进行分析的基础上,利用缓冲区由内向外逐层剖析,探讨长沙都市区近20年来城市扩张格局及其对生境质量的影响。结果表明：①长沙都市区建设用地面积从170.26 km²增至487.19 km²;三环线以内建设用地快速扩张,从三环线起向外扩张逐渐放缓;②生境质量中等及以上的区域占比从1995年的43.49%下降到2015年的27.22%,生境质量平均值则相应地从0.46下降到0.31,且退化最明显的区域从核心外围区(5-10号缓冲区)外移到三环线附近(10-15号缓冲区);③各圈层建设用地扩张强度与生境质量变化之间存在显著的空间负相关性,生境质量变化对城市扩张响应最强烈的区域始终位于核心外围区;④建设用地空间布局零散和几何形态不规则程度的增加加剧了生境质量的退化,并在三环线附近区域(10-15号缓冲区)表现最为明显,应成为未来长沙都市区城乡规划和生态管控的重点区域。     

都市农业加工型企业的发展机理与模式

都市农业是城市化进程中崭新的农业形态,但缺乏对其组织形式和生产方式的实证研究。本文基于对互润(国际)食品集团的调查实例,详细分析了都市农业加工型企业的成长机理,指出制度平台、政府行为和社区沟通是企业发展的外层机理,是企业平稳运行的基础;生产经营活动及其不断的扩张构成了企业发展的内层机理;创新和企业管理及市场的内、外部控制所形成的内核机理是企业发展的核心动力。据此,文章总结了都市农业加工型企业的发展模式,并就都市农业加工型企业如何发展提出了建议。     

Scale effects in food environment research: Implications from assessing socioeconomic dimensions of supermarket accessibility in an eight-county region of South Carolina

Choice of neighborhood scale affects associations between environmental attributes and health-related outcomes. This phenomenon, a part of the modifiable areal unit problem, has been described fully in geography but not as it relates to food environment research. Using two administrative-based geographic boundaries (census tracts and block groups), supermarket geographic measures (density, cumulative opportunity and distance to nearest) were created to examine differences by scale and associations between three common U.S. Census–based socioeconomic status (SES) characteristics (median household income, percentage of population living below poverty and percentage of population with at least a high school education) and a summary neighborhood SES z-score in an eight-county region of South Carolina. General linear mixed-models were used. Overall, both supermarket density and cumulative opportunity were higher when using census tract boundaries compared to block groups. In analytic models, higher median household income was significantly associated with lower neighborhood supermarket density and lower cumulative opportunity using either the census tract or block group boundaries, and neighborhood poverty was positively associated with supermarket density and cumulative opportunity. Both median household income and percent high school education were positively associated with distance to nearest supermarket using either boundary definition, whereas neighborhood poverty had an inverse association. Findings from this study support the premise that supermarket measures can differ by choice of geographic scale and can influence associations between measures. Researchers should consider the most appropriate geographic scale carefully when conducting food environment studies.     

基于栅格的关中平原城市群人居环境质量综合评价

基于自然与人文多重栅格数据,构建人居环境质量综合指数评价模型,分析2015年关中平原城市群人居环境的空间分异格局,并对人口分布与人居环境质量的协同性进行探讨。结果表明:(1)人居自然环境呈现出自东向西,由山地、高原向平原、谷地依次递减的空间分布格局,受地形影响最为明显,地形起伏度与人居自然环境呈负相关关系。(2)人居人文环境表现出平原低、山区高,城镇高于乡村的空间分布格局,受城市行政层级影响显著。(3)关中平原城市群人居环境综合质量指数介于0.216~0.716之间,呈现出以关中平原、汾河谷地向外梯级递减的带状空间分布格局。(4)关中平原城市群人口密度与人居环境质量空间分布显著一致,总体呈现出平原高于山地,城市高于乡村的空间分布规律,人居环境质量越高,人口密度越大,土地利用也越充分。     

Effect of copper on the growth of shrimps Litopenaeus vannamei: water parameters and copper budget in a recirculating system

Shrimps( Litopenaeus vannamei) were intensively cultured in a recirculating aquaculture system for 98 days to investigate effects of 0.3 mg/L Cu on its performance, Cu budget, and Cu distribution. Shrimps in Cu-treated systems had greater mean final weight(11.10 vs 10.50 g), body length(107.23 vs 106.42 mm), survival rate(67.80% vs 66.40%), and yield(6.42 vs 5.99 kg/m 3), and lower feed conversion ratio(1.20 vs 1.29) than those in control systems but the differences were not significant. Vibrio numbers remained stable(10 4 –10 6 colony forming units/mL) in the rearing tanks of both control and treated systems. Total ammonium-N, nitrite-N, nitrate-N, pH, chemical oxygen demand, 5-day carbonaceous biochemical oxygen demand, and total suspended solids were similar in controls and treatments. Dissolved Cu concentration in the treated systems decreased from 0.284 to 0.089 mg/L while in the control systems it increased from 0.006 2 to 0.018 mg/L. The main sources of Cu in the treated systems were the artificially added component(75.7% of total input), shrimp feed(21.0%), water(2.06%), and shrimp biomass(1.22%). The major outputs of Cu occurred via the mechanical filter(41.7%), water renewal(15.6%), and draining of the sediment trap(15.1%). The foam fractionator removed only 0.69% of total Cu input. Harvested shrimp biomass accounted for 11.68% of Cu input. The Cu concentration of shrimps in the Cu-treated systems(30.70 mg/kg wet weight) was significantly higher than that in control systems(22.02 mg/kg). Both were below the maximum permissible concentration(50 mg/kg) for Cu in seafood for human consumption in China. Therefore, recirculating systems can be used for commercial on-growing of Litopenaeus vannamei without loss of shrimp quality, even in water polluted by 0.30 mg/L Cu. The mechanical filter is the main route for Cu removal.     

天津市地震前兆台网的运行监控与维护管理

介绍天津市地震前兆台网的基本概况以及前兆台网部的职责任务;阐述仪器设备运行监控、观测数据质量监控的方式与方法;总结在仪器设备、技术系统维护过程中解决的一些关键技术问题;最后提出了关于仪器和软件系统的一些问题与建议。